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Region 2 of the Escherichia coli K5 capsule gene cluster encoding proteins for the biosynthesis of the K5 polysaccharide
Author(s) -
Petit Chantal,
Rigg Gordon P.,
Pazzani Carlo,
Smith Annabel,
Sieberth Veit,
Stevens Mark,
Boulnois Graham,
Jann Klaus,
Roberts Ian S.
Publication year - 1995
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1995.mmi_17040611.x
Subject(s) - biology , gene cluster , escherichia coli , gene , nucleic acid sequence , homology (biology) , microbiology and biotechnology , biochemistry , peptide sequence , promoter , transferase , structural gene , amino acid , enzyme , gene expression
The nucleotide sequence of region 2 of the Escherichia coli K5 capsule gene cluster has been determined. This region, essential for the biosynthesis of the K5 poly‐saccharide, contained four genes, termed kfiA‐D . The G+C ratio was 33.4%, which was lower than the typical G+C ratio for E. coli and that of the flanking regions 1 and 3 in the K5 capsule gene cluster. Three major RNA transcripts were detected within region 2 by Northern blotting and three promoters located by transcript mapping. Promoter activity was confirmed by promoter‐probe analysis. The predicted amino acid sequence of KfiC had homology to a number of glycosyl transferase enzymes and overexpression of the kfiC gene resulted in increased K5 transferase activity. The predicted amino acid sequence of KfiD had homology to a number of NAD‐dependent dehydrogenase enzymes and was demonstrated to be a UDP‐glucose dehydrogenase that catalyses the formation of UDP‐glucuronic acid from UDP‐glucose.